The habitat-specific effects of highway proximity on ground-dwelling arthropods: Implications for biodiversity conservation

The total length of highways worldwide has increased continuously over recent decades. Highways and their roadside verges may substantially affect species dispersal, and the ecological effects of highways often extend to neighbouring areas. This study investigated the effects of highways on assemblages of ground-dwelling arthropods in neighbouring forest and open habitats. In total, 24 sites within five highway segments situated in the Czech Republic were sampled using transects of pitfall traps placed at increasing distances (0, 50 and 100 m) from the edge of highway verges. The total catch size and species richness of ground-dwelling spiders and beetles varied more strongly with distance from the highway edge in forest habitats than in open habitats. Species composition of both spiders and beetles was significantly affected by distance from the highway edge in open habitats as well as in forest habitats. In general, the species richness of forest specialist beetles (but not of spiders) was negatively affected by highway proximity in forested sites, whereas habitat generalists and open habitat specialists (both spiders and beetles) benefited from proximity to a highway in both forest and open habitats. Our results indicate that highway verges may potentially enhance local assemblages of ground dwelling spiders and beetles because they provide suitable sites (in intensively managed open landscapes) or dispersal corridors (in forested landscapes) for habitat generalists and open habitat specialist species. However, negative effects on forest specialists must also be considered, especially in landscapes with little forest. The landscape context should be given substantial consideration in future decisions about highway location because possible threats to forest specialists and benefits for other species must be recognised and balanced.